Low temperature vibration damping pressure sensitive adhesives and constructions

ABSTRACT

This disclosure relates to viscoelastic damping materials and constructions which may demonstrate low temperature performance and adhesion and which may be used in making vibration damping composites. Viscoelastic damping materials and constructions may include polymers or copolymers of monomers according to formula I: 
       CH 2 ═CHR 1 —COOR 2   [I]
 
     wherein R 1  is H, CH 3  or CH 2 CH 3  and R 2  is a branched alkyl group containing 12 to 32 carbon atoms.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. Ser. No. 14/369,316, filed Jun.27, 2014, pending, which is a national stage filing under 35 U.S.C. 371of PCT/US2012/071650, filed Dec. 26, 2012, which claims priority to U.S.Provisional Patent Application No. 61/581,374, filed Dec. 29, 2011 andU.S. Provisional Patent Application No. 61/675,536 filed Jul. 25, 2012,the disclosures of which are incorporated by reference in their entiretyherein.

FIELD OF THE DISCLOSURE

This disclosure relates to viscoelastic damping materials andconstructions which may demonstrate low temperature performance andadhesion and which may be used in making vibration damping composites.

SUMMARY OF THE DISCLOSURE

Briefly, the present disclosure provides a viscoelastic damping materialcomprising: a) a copolymer of: i) at least one monomer according toformula I:

CH₂═CHR¹—COOR²  [I]

wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branched alkyl groupcontaining 12 to 32 carbon atoms, and ii) at least one second monomer;and b) at least one adhesion-enhancing material. In some embodiments,the adhesion-enhancing material is one of: inorganic nanoparticles,core-shell rubber particles, polybutene materials, or polyisobutenematerials. Typically R² is a branched alkyl group containing 15 to 22carbon atoms. Typically R¹ is H or CH₃. Typically second monomers areacrylic acid, methacrylic acid, ethacrylic acid, acrylic esters,methacrylic esters or ethacrylic esters. The viscoelastic dampingmaterial may additionally comprise a plasticizer.

In another aspect, the present disclosure provides a viscoelasticdamping material comprising a copolymer of: i) at least one monomeraccording to formula I:

CH₂═CHR¹—COOR²  [I]

wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branched alkyl groupcontaining 12 to 32 carbon atoms, and ii) a monofunctional silicone(meth)acrylate oligomer. Typically R² is a branched alkyl groupcontaining 15 to 22 carbon atoms. Typically R¹ is H or CH₃. Theviscoelastic damping material may additionally comprise a plasticizer.

In another aspect, the present disclosure provides a viscoelasticconstruction comprising: a) at least one viscoelastic layer comprising apolymer or copolymer of at least one monomer according to formula I:

CH₂═CHR¹—COOR²  [I]

wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branched alkyl groupcontaining 12 to 32 carbon atoms; bound to b) at least one PSA layercomprising a pressure sensitive adhesive. In some embodiments, theviscoelastic layer is bound to at least two layers comprising a pressuresensitive adhesive. Typically R² is a branched alkyl group containing 15to 22 carbon atoms. Typically R¹ is H or CH₃. In some embodiments, theviscoelastic layer comprises copolymer which is a copolymer of at leastone second monomer selected from acrylic acid, methacrylic acid,ethacrylic acid, acrylic esters, methacrylic esters, or ethacrylicesters. In some embodiments, the PSA layer comprises an acrylic pressuresensitive adhesive. In some embodiments, the PSA layer comprises anacrylic pressure sensitive adhesive which is a copolymer of acrylicacid.

In another aspect, the present disclosure provides a viscoelasticconstruction comprising: a) discrete particles of a polymer or copolymerof at least one monomer according to formula I:

CH₂═CHR¹—COOR²  [I]

wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branched alkyl groupcontaining 12 to 32 carbon atoms; dispersed in b) a PSA layer comprisinga pressure sensitive adhesive. In some embodiments, the PSA layercomprises an acrylic pressure sensitive adhesive. In some embodiments,the PSA layer comprises an acrylic pressure sensitive adhesive which isa copolymer of acrylic acid.

In another aspect, the present disclosure provides a vibration dampingcomposite comprising a viscoelastic damping material or a vibrationdamping composite of the present disclosure adhered to at least onesubstrate. In some embodiments, the material or construction is adheredto at least two substrates. In some embodiments, at least one substrateis a metal substrate.

DETAILED DESCRIPTION

The present disclosure provides material sets and constructions thatdemonstrate a pressure sensitive adhesive (PSA) that offers bothvibration damping performance at very low temperatures and highfrequencies as well as substantial adhesive performance and durabilitywhen used with a variety of substrates over a wide range oftemperatures. The combination of both low temperature damping andadhesive performance attained using a single material set orconstruction represents a significant technical challenge in the fieldof visco-elastic damping materials. In some embodiments of the presentdisclosure, this is achieved through the use of specialty acrylicmaterials, specific additives, multi-layer construction, or combinationsof the above.

The present disclosure provides material sets and constructions thatdemonstrate a pressure sensitive adhesive that offers both vibrationdamping performance at very low temperatures and high frequencies aswell as substantial adhesive performance and durability when used with avariety of substrates over a wide range of temperatures. In someembodiments, materials or constructions according to the presentdisclosure exhibit high tan delta, as measured by Dynamic MechanicalAnalysis (DMA) at −55° C. and 10 Hz as described in the examples below.In some embodiments, materials or constructions according to the presentdisclosure exhibit tan delta (as measured by Dynamic Mechanical Analysis(DMA) at −55° C. and 10 Hz as described in the examples below) ofgreater than 0.5, in some embodiments greater than 0.8, in someembodiments greater than 1.0, in some embodiments greater than 1.2, andin some embodiments greater than 1.4. In some embodiments, materials orconstructions according to the present disclosure exhibit high peeladhesion, as measured as described in the examples below. In someembodiments, materials or constructions according to the presentdisclosure exhibit peel adhesion (as measured as described in theexamples below) of greater than 10 N/dm, in some embodiments greaterthan 20 N/dm, in some embodiments greater than 30 N/dm, in someembodiments greater than 40 N/dm, in some embodiments greater than 50N/dm, and in some embodiments greater than 60 N/dm. In some embodiments,materials or constructions according to the present simultaneouslyachieve high tan delta, at one or more of the levels described above,and high peel strength, at one or more of the levels described above.

In some embodiments, viscoelastic damping materials according to thepresent disclosure include long alkyl chain acrylate copolymers whichare copolymers of monomers including one or more long alkyl chainacrylate monomers. The long alkyl chain acrylate monomers are typicallyacrylic acid, methacrylic acid or ethacrylic acid esters but typicallyacrylic acid esters. In some embodiments, the side chain of the longalkyl chain contains 12 to 32 carbon atoms (C12-C32), in someembodiments at least 15 carbon atoms, in some embodiments at least 16carbon atoms, in some embodiments 22 or fewer carbon atoms, in someembodiments 20 or fewer carbon atoms, in some embodiments 18 or fewercarbon atoms, and in some embodiments 16-18 carbon atoms. Typically, thelong alkyl chain has at least one branch point to limit crystallinity inthe formed polymer that may inhibit damping performance. Long chainalkyl acrylates with no branch points may be used in concentrations lowenough to limit crystallinity of the formed polymer at applicationtemperatures. In some embodiments, additional comonomers are selectedfrom acrylic acid, methacrylic acid or ethacrylic acid, but typicallyacrylic acid. In some embodiments, additional comonomers are selectedfrom acrylic, methacrylic or ethacrylic esters, but typically acrylicesters.

In some embodiments, the long alkyl chain acrylate copolymers compriseadditional comonomers or additives that join in the polymerizationreaction, which imparting adhesive properties. Such comonomers mayinclude polyethylene glycol diacrylates.

In some embodiments, the long alkyl chain acrylate copolymers compriseadditional comonomers or additives that join in the polymerizationreaction, which can help to impart greater adhesive properties throughmodulation of the rheological properties of the viscoelastic dampingcopolymer, or through the addition of functional groups. Such comonomersmay include but are not limited to (meth)acrylic acid, hydroxyethyl(meth)acrylate, dimethylaminoethyl (meth)acrylate, monofunctionalsilicone (meth)acrylates, and isobornyl (meth)acrylate.

In some embodiments, the viscoelastic damping copolymer may becrosslinked to improve the durability and adhesion properties of thematerial. Such crosslinking agents can include but are not limited tophotoactivated crosslinkers such as benzophenones, or2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-triazine. Crosslinkingagents can also include copolymerizable multifunctional acrylates suchas polyethylene glycol diacrylate or hexanediol diacrylate as examples.

In some embodiments the viscoelastic damping copolymer may bepolymerized through all known polymerization methods including thermallyactivated or photoinitiated polymerization. Such photopolymerizationprocesses can include for example common photoinitiators such asdiphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide.

In some embodiments, viscoelastic damping materials according to thepresent disclosure include long alkyl chain acrylate copolymers andadditional adhesion-enhancing materials which impart adhesiveproperties. Such additional adhesion-enhancing materials may includepolybutenes, silicones, or polyisobutenes. Such additionaladhesion-enhancing materials may also be particulate materials. Suchparticulate adhesion-enhancing materials may include fumed silica,core-shell rubber particles, or isostearyl acrylate microspheres.

In some embodiments, long alkyl chain acrylate copolymers according tothe present disclosure form a part of a multilayer viscoelasticconstruction. In some embodiments, the long alkyl chain acrylatecopolymers according to the present disclosure form a viscoelasticdamping layer of a two-layer viscoelastic construction, the second,attached layer being a layer of more highly adhesive material over abroader temperature range. In some embodiments, the long alkyl chainacrylate copolymers according to the present disclosure form aviscoelastic damping core layer of a multilayer viscoelasticconstruction, sandwiched between two layers of more highly adhesivematerial. In some embodiments, the long alkyl chain acrylate copolymersaccording to the present disclosure form a layer of a multilayerviscoelastic construction which additionally comprises at least onelayer of more highly adhesive material. In some embodiments, the longalkyl chain acrylate copolymers according to the present disclosure forman interior layer of a multilayer viscoelastic construction whichadditionally comprises at least two layers of more highly adhesivematerial. In some embodiments, the more highly adhesive material is anacrylic PSA material.

In some embodiments, a two-layer viscoelastic construction comprises aviscoelastic layer attached to a second layer which is a layer of morehighly adhesive material. In some embodiments, the two-layerviscoelastic construction is made by lamination of a viscoelastic layerto an adhesive layer. In some embodiments, the two-layer viscoelasticconstruction is made by application of an adhesive tape to aviscoelastic layer. In some embodiments, the two-layer viscoelasticconstruction is made by application of an adhesive in liquid oraerosolized form to a viscoelastic damping layer to provide greateradhesion to the damping layer. In some embodiments, the two-layerviscoelastic construction is made by application of an adhesive in pasteform to a viscoelastic layer. In some embodiments, a two-layerviscoelastic construction is provided in the form of a roll, sheet, orpre-cut article. In some embodiments, a two-layer viscoelasticconstruction is made shortly prior to use by application of an adhesiveto a viscoelastic layer. In some embodiments, a two-layer viscoelasticconstruction is made in situ by application of an adhesive to asubstrate followed by application of a viscoelastic layer to theadhesive.

In some embodiments, the multilayer viscoelastic construction comprisesa viscoelastic layer sandwiched between two layers of more highlyadhesive material. In some embodiments, the multilayer viscoelasticconstruction is made by lamination of a viscoelastic layer to at leastone adhesive layer. In some embodiments, the multilayer viscoelasticconstruction is made by application of an adhesive tape to at least oneside of a viscoelastic layer. In some embodiments, the multilayerviscoelastic construction is made by application of an adhesive inliquid form to at least one side of a viscoelastic layer. In someembodiments, the multilayer viscoelastic construction is made byapplication of an adhesive in paste form to at least one side of aviscoelastic layer. In some embodiments, a multilayer viscoelasticconstruction is provided in the form of a roll, sheet, or pre-cutarticle. In some embodiments, a multilayer viscoelastic construction ismade shortly prior to use by application of an adhesive to aviscoelastic layer. In some embodiments, a multilayer viscoelasticconstruction is made in situ by application of an adhesive to asubstrate followed by application of a viscoelastic layer to theadhesive, followed by application to the viscoelastic layer ofadditional adhesive or an additional adhesive-bearing substrate. In someembodiments, the multilayer construction is made in-situ by applicationof the viscoelastic damping composition in liquid form between twoadhesive layers followed by a subsequent cure of the damping layer toform the viscoelastic damping copolymer.

The materials or constructions according to this disclosure may beuseful for aerospace applications in which maximum damping performanceof high frequency vibration energy is required at very low temperatures,in combination with good adhesion properties.

Objects and advantages of this disclosure are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this disclosure.

Examples

Unless otherwise noted, all reagents were obtained or are available fromSigma-Aldrich Company, St. Louis, Mo., or may be synthesized by knownmethods. Unless otherwise reported, all ratios are by weight percent.

The following abbreviations are used to describe the examples:

° F.: degrees Fahrenheit

° C.: degrees Centigrade

cm: centimeters

g/cm³: grams per cubic centimeter

Kg: kilograms

Kg/m³: kilograms per cubic meter

mil: 10⁻³ inches

mJ/cm²: milliJoules per square centimeter

ml: milliliters

mm: millimeters

micrometers

N/dm: Newtons per decimeter

pcf: pounds per cubic foot

pph: parts per hundred

Test Methods Peel Adhesion Test (PAT)

The force required to peel the test material from a substrate at anangle of 180 degrees was measured according to ASTM D 3330/D 3330M-04.Using a rubber roller, the adhesive sample was manually laminated onto aprimed 2 mil (50.8 μm) polyester film, obtained under the tradedesignation “HOSTAPHAN 3SAB” from Mitsubishi Plastics, Inc., Greer,S.C., and allowed to dwell for 24 hours at 23° C./50% relative humidity.A 0.5×6 inches (1.27×12.7 cm) section was cut from the laminated filmand taped to either a 0.10 inch (2.54 mm) or 0.20 inch (5.08 mm) thick,Shore A 70, 320 Kg/m³ polyether-polyurethane foam, or a grade 2024aluminum test coupon, obtained from Aerotech Alloys, Inc., Temecula,Calif. The tape was then manually adhered onto the test coupon using a 2Kg rubber roller and conditioned for 24 hours at 23° C./50% relativehumidity. The peel adhesive force was then determined using a tensileforce tester, model “SP-2000”, obtained Imass Inc., Accord, Mass., at aplaten speed of 12 in./min (0.305 m/min.). Three tape samples weretested per example or comparative, and the average value reported inN/dm. Also reported are the failure modes, abbreviated as follows:

-   -   A: Adhesive tape cleanly delaminated from the substrate    -   2B: Two-bond failure, wherein the adhesive tape delaminated from        the carrier backing    -   C: Cohesive failure, wherein the adhesive layer ruptured,        leaving material on both the backing and the substrate.

Dynamic Mechanical Analysis (DMA)

Dynamic Mechanical Analysis (DMA) was determined using a parallel platerheometer, model “AR2000” obtained from TA Instruments, New Castle, Del.Approximately 0.5 grams of visco-elastic sample was centered between thetwo 8 mm diameter, aluminum parallel plates of the rheometer andcompressed until the edges of the sample were uniform with the edges ofthe plates. The temperature of the parallel plates and rheometer shaftswas then raised to 40° C. and held for 5 minutes. The parallel plateswere then oscillated at a frequency of 10 Hz and a constant strain of0.4% whilst the temperature was ramped down to −80° C. at a rate of 5°C./min. Storage modulus (G′), and tan delta were then determined.

Glass Transition Temperature (Tg)

Tan delta, the ratio of G″/G′, was plotted against temperature. Tg istaken as the temperature at maximum tan delta curve.

Damping Loss Factor (DLF)

A composite material was prepared for Damping Loss Factor as follows. Anominally 6 by 48 inch by 7 mil (15.24 by 121.92 cm by 0.178 mm) stripof aluminum was cleaned with a 50% aqueous solution of isopropyl alcoholand wiped dry. A primer, type “LORD 7701”, obtained from LordCorporation, Cary, N.C., was applied to a nominally 6 by 48 by 0.1 inch(15.24 by 121.92 cm by 2.54 mm) strip of 20 pcf (0.32 g/cm³) whiteforaminous micro cellular high density polyurethane foam. The adhesivetape was applied to the aluminum strip, nipped together to ensure wetout, then applied to the primed surface of the high density urethane. A5 mil (127 μm) adhesive transfer tape, obtained under the tradedesignation “VHB 9469PC” obtained from 3M Company, St. Paul, Minn., wasthen applied on the opposite side of the urethane strip. The resultingcomposite material cut into 2 by 24 inch (5.08 by 60.96 cm) samples andapplied to a 3×40 inch×0.062 mil (7.62×101.4 cm×1.58 mm) aluminum beam.

The beam was suspended by its first nodal points, and the center of thebeam mechanically coupled to an electromagnetic shaker model “V203” fromBrüel & Kjær North America, Inc., Norcross, Ga., via an inline forcetransducer, model “208M63” from PCB Piezotronics, Inc., Depew, N.Y., ina thermally controlled chamber at temperatures of −10° C., −20° C. and−30° C. On the opposite side of the beam to the inline force transducerwas mounted an accelerometer, model “353B16 ICP”, also fromPiezotronics, Inc. A broad band signal was sent to the electromagneticshaker and the force the shaker excerpted on the beam was measured, aswas the resulting acceleration of the beam. The frequency responsefunction (FRF) was calculated from the cross spectrum of the measuredacceleration and force, and from the magnitude of the FRF, peakamplitudes were used to identify the modal frequencies. The half powerbandwidth around each modal frequency was also identified as the span offrequencies between the −3 dB amplitude points above and below the modalfrequency. The ratio of the half power bandwidth to modal frequency wascalculated and reported as the Damping Loss Factor.

Materials

Abbreviations for the reagents used in the examples are as follows:

-   A-75: A benzoyl peroxide, obtained under the trade designation    “LUPEROX A75” from Arkema, Inc. Philadelphia, Pa.-   AA: Acrylic acid, obtained from Sigma-Aldrich Company, St. Louis,    Mo.-   BDDA: 1,4-butanediol diacrylate, obtained under the trade    designation “SR213” from Sartomer, USA, LLC, Exton, Pa.-   DMAEMA: N,N-dimethylaminoethylmethacrylate, obtained from    Sigma-Aldrich Company.-   E-920: A methacrylate-butadiene-styrene copolymer, obtained under    the trade designation “CLEARSTRENGTH E-920” from Arkema, Inc., King    of Prussia, Pa.-   F-85E: Ester of hydrogenated rosin, obtained under the trade    designation “FORAL 85-E” from Eastman Chemical Company, Kingsport,    Tenn.-   HDDA: 1,6-hexanediol diacrylate, obtained under the trade    designation “SR238B” from Sartomer, USA, LLC.-   I-651: 2,2-Dimethoxy-1,2-diphenylethan-1-one, obtained under the    trade designation “IRGACURE 651” from BASF Schweiz AG, Basel,    Switzerland.-   IOA: Isooctyl acrylate, obtained under the trade designation “SR440”    from Sartomer, USA, LLC.-   IOTMS: Isooctyltrimethoxysilane, obtained from Gelest, Inc.,    Morrisville, Pa.-   ISF-16: 2-hexyldecanol, obtained under the trade designation “ISOFOL    16” from Sasol North America, Inc., Houston, Tex.-   ISF-18: 2-hexyldodecanol, obtained under the trade designation    “ISOFOL 18” from Sasol North America, Inc.-   ISF-24: 2-decyltetradecanol, obtained under the trade designation    “ISOFOL 24” from Sasol North America, Inc.-   KB-1: 2,2-dimethoxy-1,2-di(phenyl)ethanone, obtained under the trade    designation “ESACURE KB1” from Lamberti USA, Inc., Conshohocken, Pa.-   L-26M50: A 50% solution of tert-butyl peroxy-2-ethylhexanoate in    mineral spirits, obtained under the trade designation “LUPEROX    26M50” from Arkema Inc.-   MTMS: Methyltrimethoxysilane, obtained from Gelest, Inc.-   N2326: A 16.4% colloidal silica dispersion, obtained under the trade    designation “NALCO 2326” from Nalco Company, Naperville, Ill.-   PB-100: Polyisobutene having a molecular weight of 250,000 obtained    under the trade designation “OPPANOL B-100” from BASF Corporation,    Freeport, Tex.-   PB-910: Polybutene, having a molecular weight of 910, obtained under    the trade designation “INDOPOL H-100” from Ineos Oligomers, League    City, Tex.-   PB-1000: Polyisobutene having a molecular weight of 1,000 obtained    under the trade designation “GLISSOPAL R-1000” from BASF    Corporation.-   PB-1900: Polybutene having a molecular weight of 2,500 obtained    under the trade designation “INDOPOL H-1900” from BASF Corporation.-   PEGDA: Polyethylene glycol (600) diacrylate, obtained under the    trade designation “SR610” from Sartomer, USA, LLC.-   R-100: A random butadiene-styrene copolymer, obtained under the    trade designation “RICON 100” from Sartomer, USA, LLC.-   R-972: A hydrophobic fumed silica, obtained under the trade    designation “AEROSIL R-972” from Evonik Degussa Corporation,    Parsippany, N.J.-   RC-902: A radiation curable silicone, obtained under the trade    designation “TEGO RC-902” from Evonik Degussa Corporation.-   S-1001: Styrene Ethylene Propylene Block Copolymer, obtained under    the trade designation “SEPTON 1001” from Kuraray Co. Ltd., Tokyo,    Japan.-   SAMV: Ammonium lauryl sulfate, obtained under the trade designation    “STEPANOL AMV” from Stepan Company, Northfield, Ill.-   T-10: Clear silicone release liner, obtained under the trade    designation “CLEARSIL T-10” from Solutia, Inc. St. Louis, Mo.-   T-50: Clear silicone release liner, obtained under the trade    designation “CLEARSIL T-50” from Solutia, Inc.-   T-145A: Silicone resin, obtained under the trade designation    “TOSPEARL 145A” from Momentive Performance Materials Holdings, LLC,    Columbus Ohio.-   TMT: 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-triazine.-   TPO: Diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, obtained    under the trade designation “DAROCUR TPO” from BASF Schweiz AG.-   467-MP: A 2 mil. (50.8 μm) adhesive transfer tape having a paper    liner, obtained under the trade designation “ADHESIVE TRANSFER TAPE    467 MP” from 3M Company.-   467-MPF: A 2 mil. (50.8 μm) adhesive transfer tape having a film    liner, obtained under the trade designation “ADHESIVE TRANSFER TAPE    467 MPF” from 3M Company    Non-commercial materials described in the examples were synthesized    as follows:-   HEDA: 2-hexa-1-decyl acrylate. 100 grams of 2-hexyl-1-decanol, 45.97    grams triethylamine and 350 grams of methylene chloride were added    to a 1 liter flask and cooled to 5° C. using an ice bath. 41.1 grams    acryloyl chloride was slowly added, dropwise over one hour, while    mechanically stirring the mixture. After 10 hours the mixture was    filtered and then concentrated under vacuum at 25° C. The remaining    resultant oil was diluted with ethyl acetate and washed with 1.0    Molar hydrochloric acid, followed by 1.0 Molar sodium hydroxide    solution, then a saturated sodium chloride solution. The organic    layer was then concentrated under vacuum at 25° C. The crude oil was    mixed with an equal amount of hexane and passed through a column of    neutral alumina to remove colored impurities, after which the    alumina was eluted with hexane. The collected filtrate was    concentrated under vacuum at 25° C., resulting in a colorless oil of    2-hexa-1-decyl acrylate.-   ISA: An isostearyl acrylate. 197.17 grams ISF-18, 78.12 grams    triethylamine and 700 grams of methylene chloride were added to a 2    liter flask and cooled to 5° C. using an ice bath. 69.86 grams    acryloyl chloride was slowly added, dropwise over one hour, while    mechanically stirring the mixture. After 10 hours the mixture was    filtered and then concentrated under vacuum at 25° C. The remaining    resultant oil was diluted with ethyl acetate and washed with 1.0    Molar hydrochloric acid, followed by 1.0 Molar sodium hydroxide    solution, then a saturated sodium chloride solution. The organic    layer was then concentrated under vacuum at 25° C. The crude oil was    mixed with an equal amount of hexane and passed through a column of    neutral alumina to remove colored impurities, after which the    alumina was eluted with hexane. The collected filtrate was    concentrated under vacuum at 25° C., resulting in a colorless oil of    100% isostearyl acrylate.-   ISA-MS: Isostearyl acrylate microspheres. Mixture A was prepared by    adding 180 grams ISA, 0.58 grams A-75 and 1.8 grams BDDA to a 500 ml    glass jar and mixed in a roller mill until dissolved. Mixture B was    prepared by adding to a 1 liter glass beaker, 420 grams distilled    water, 7.2 grams SAMV and 1.8 grams BDDA, and dispersing until    homogeneous using a high shear mixer, model “OMNI-MIXER” from OCI    Instruments, Waterbury, Conn. Mixture A was then added to the glass    beaker and high shear mixing continued for approximately 2 minutes    until very small droplets of about 3 microns diameter were formed.    The product was then transferred to a 1 liter glass reactor equipped    with a mechanical stirrer. The reactor was filled with nitrogen gas,    heated to 65° C., and held at this temperature, with continuous    stirring, for 24 hours, after which it was cooled to 23° C. The    resulting suspension was filtered through a cheese cloth to remove    agglomerates and coagulated using 500 mls isopropanol. The coagulum    was then dried in an oven at 45° C. for approximately 16 hours.

Single-Layer Constructions Sample 1

A 25 dram (92.4 mls) glass jar was charged with 19.6 grams HEDA, 0.4grams AA and 0.008 grams I-651. The monomer mixture was stirred for 30minutes at 21° C., purged with nitrogen for 5 minutes, and then exposedto low intensity ultraviolet light, type “BLACK RAY XX-15BLB” obtainedfrom Fisher Scientific, Inc., Pittsburgh, Pa., until a coatablepre-adhesive polymeric syrup was formed. An additional 0.032 grams I-651and 0.03 grams PEGDA were blended into the polymeric syrup using a highspeed mixer, model “DAC 150 FV” obtained from FlackTek, Inc., Landrum,S.C. The polymeric syrup was then coated between silicone release linersT-10 and T-50 at an approximate thickness of 8 mils (203.2 μm) and curedby means of UV-A light at 2,000 mJ/cm².

Samples 2-6

The procedure generally described in Sample 1 was repeated, according tothe quantities of acrylate monomers listed in Table 1. Physicalcharacteristics of the resultant cured adhesive coatings are listed inTable 2.

TABLE 1 Composition Additives (as pph of % Acrylate Acrylate) SampleHEDA IOA ISA AA I-651 PEGDA 1 98.0 0 0 2.0 0.20 0.23 2 93.5 0 0 6.5 0.200.23 3 0 0 98.0 2.0 0.20 0.23 4 100.0 0 0 0 0.20 0.23 5 0 0 100.0 0 0.200.23 6 0 93.5 0 6.5 0.20 0.23

TABLE 2 Adhesion To Adhesion To Polyurethane Aluminum Peel Peel StorageTan Adhesive Adhesive Modulus Delta Force Failure Force Failure @ @Sample (N/dm) Mode (N/dm) Mode −55° C. −55° C. 1 26 A 21 A 3.3 × 10⁶0.96 2 21 A 48 A 2.0 × 10⁷ 0.72 3 24 A 15 A 1.3 × 10⁷ 1.09 4 3 C 3 C 1.1× 10⁶ 1.50 5 10 A 4 A 3.5 × 10⁶ 1.36 6 25 A 64 A 3.1 × 10⁸ 0.10

Sample 7

A 25 dram (92.4 mls) glass jar was charged with 19.6 grams HEDA, 0.4grams AA and 0.008 grams I-651. The monomer mixture was stirred for 30minutes at 21° C., purged with nitrogen for 5 minutes, and exposed tothe low intensity ultraviolet light until a coatable pre-adhesivepolymeric syrup was formed. An additional 0.032 grams I-651, 0.046 gramsPEGDA and 2.0 grams R-972 were subsequently blended into the polymericsyrup using the high speed mixer. The polymeric syrup was then coatedbetween silicone release liners at an approximate thickness of 8 mils(203.2 μm) and cured by means of UV-A light at 2000 mJ/cm².

Samples 8-33

The procedure generally described in Sample 7 was repeated, whereinvarious amounts of fumed silica, plasticizer, polybutenes,polyisobutenes, silicones, core-shell rubber particles and isostearylacrylate microspheres, were blended into the pre-adhesive polymericsyrup according to the quantities listed in Table 3. Physicalcharacteristics of the resultant cured adhesive coatings are listed inTable 4.

TABLE 3 Composition % Acrylate Additives (as pph of Acrylate) SampleHEDA AA ISA R-972 PEGDA TMT ISF-24 PB-910 PB-1000 PB-1900 7 99.0 1.0 010.0 0.23 0 0 0 0 0 8 98.0 2.0 0 7.0 0.23 0 0 0 0 0 9 98.0 2.0 0 10.00.23 0 0 0 0 0 10 98.0 2.0 0 13.0 0.23 0 0 0 0 0 11 0 2.0 98.0 7.0 0.230 0 0 0 0 12 0 2.0 98.0 10.0 0.23 0 0 0 0 0 13 93.5 5.0 0 10.0 0.23 0 00 0 0 14 98.0 2.0 0 10.0 0.23 0 4.0 0 0 0 15 98.0 2.0 0 10.0 0.23 0 5.00 0 0 16 98.0 2.0 0 0 0.20 0 0 0 5.0 0 17 98.0 2.0 0 5.0 0.20 0 0 0 5.00 18 98.0 2.0 0 5.0 0.20 0 0 0 10.0 0 19 98.0 2.0 0 5.0 0.20 0 0 5.0 0 020 98.0 2.0 0 5.0 0.20 0 0 0 0 5.0 21 98.0 2.0 0 5.0 0 0.15 0 0 15.0 022 98.0 2.0 0 5.0 0.20 0 0 0 5.0 0 Composition % Acrylate Additives (aspph of Acrylate) Sample HEDA AA IOA ISA-MS PEGDA TMT T-145A RC-902 HDDAE-920 23 0 6.5 93.5 0 0 0 5.0 0 0 0 24 0 6.5 93.5 0 0 0 10.0 0 0 0 2593.5 6.5 0 0 0 0 5.0 0 0 0 26 98.0 2.0 0 0 0 0 0 10.0 0.08 0 27 98.0 2.00 0 0.20 0 0 0 0 10.0 28 98.0 2.0 0 0 0 0.15 0 0 0 5.0 29 0 6.5 93.5 5.00.23 0 0 0 0 0 30 0 6.5 93.5 10.0 0.23 0 0 0 0 0 31 93.5 6.5 0 10.0 0.230 0 0 0 0 Composition % Acrylate Additives (as pph of Acrylate) SampleHEDA AA IOA PEGDA HDDA PB-100 S-1001 D-TPO 32 100.0 0 0 0 0.1 6.0 0 0.333 100.0 0 0 0 0.1 0 10.0 0.3

TABLE 4 Adhesion To Adhesion To Polyurethane Aluminum Peel Peel StorageTan Adhesion Adhesion Modulus Delta Force Failure Force Failure @ @Sample (N/dm) Mode (N/dm) Mode −55° C. −55° C. 7 2 A 1 A 1.4 × 10⁶ 1.678 22 A 35 A 1.2 × 10⁷ 0.96 9 26 A 27 A 4.0 × 10⁷ 0.92 10 23 A 24 A 3.6 ×10⁷ 0.89 11 153 C 120 C 1.8 × 10⁷ 1.04 12 55 2B  77 2B  1.3 × 10⁷ 1.0113 24 A 47 2B  2.9 × 10⁷ 0.64 14 96 C 92 C 2.6 × 10⁷ 0.97 15 76 C 69 C1.8 × 10⁶ 0.95 16 26 A 22 A 1.5 × 10⁶ 1.15 17 85 A 88 2B  7.7 × 10⁶ 1.1318 77 C 79 C 1.1 × 10⁷ 1.22 19 57 A 39 A 8.1 × 10⁶ 1.15 20 55 A 39 A 1.4× 10⁷ 1.08 21 54 A 48 A 8.4 × 10⁶ 1.30 22 125 C 56 A 9.1 × 10⁶ 1.04 2316 A 37 A 3.5 × 10⁸ 0.58 24 18 A 36 A 3.8 × 10⁸ 1.26 25 20 A 22 A 3.0 ×10⁷ 0.70 26 1 A 0 A 1.3 × 10⁶ 1.16 27 16 A 12 A 7.2 × 10⁶ 1.01 28 15 A16 A 1.4 × 10⁷ 1.06 29 31 A 77 A 2.7 × 10⁶ 1.10 30 28 A 97 A 3.2 × 10⁶1.10 31 26 A 68 A 5.2 × 10⁵ 0.86 32 5 A 4 A 4.8 × 10⁶ 1.35 33 2 A 3 A7.7 × 10⁶ 1.18

Visco-Elastic Core VEC-1

A 25 dram (92.4 mls) glass jar was charged with 19.8 grams HEDA, 0.2grams DMAEMA and 0.008 grams I-651. The monomer mixture was stirred for30 minutes at 21° C., purged with nitrogen for 5 minutes, and exposed tothe low intensity ultraviolet light until a coatable pre-adhesivepolymeric syrup was formed. An additional 0.032 grams I-651 and 0.03grams TMT were subsequently blended into the polymeric syrup using thehigh speed mixer. The polymeric syrup was then coated between siliconerelease liners T-10 and T-50 at an approximate thickness of 8 mils(203.2 μm) and cured by means of UV-A light at 2,000 mJ/cm².

Visco-Elastic Cores VEC-2-VEC-10

The procedure generally described in VEC-1 was repeated, according tothe compositions listed in Table 5. With respect to VEC-6, the nominalthickness was 16 mils (406.4 μm). Physical characteristics of thevisco-elastic cores are listed in Table 6.

TABLE 5 Composition Additives Visco-Elastic % Acrylate (as pph ofAcrylate) Core HEDA ISA IOA DMAEMA TMT PEGDA VEC-1 99.0 0 0 1.0 0.15 0VEC-2 98.0 0 0 2.0 0.15 0 VEC-3 96.0 0 0 4.0 0.15 0 VEC-4 0 96.0 0 4.0 00.23 VEC-5 0 0 96.0 4.0 0 0.23 VEC-6 0 96.0 0 4.0 0.15 0 VEC-7 0 90.010.0 0 0.15 0 VEC-8 0 100.0 0 0 0.15 0 VEC-9 0 0 100.0 0 0.15 0  VEC-100 75.0 25.0 0 0.15 0

TABLE 6 Core Thickness Storage Modulus Tan Delta Visco-Elastic Core mils(μm) @ −55° C. @ −55° C. VEC-1 8 (203.2) 2.4 × 10⁶ 1.33 VEC-2 8 (203.2)3.2 × 10⁶ 1.32 VEC-3 8 (203.2) 5.1 × 10⁶ 1.32 VEC-4 8 (203.2) 6.0 × 10⁶1.36 VEC-5 8 (203.2) 2.6 × 10⁸ 0.13 VEC-6 16 (406.4)  5.9 × 10⁶ 1.37VEC-7 8 (203.2) 1.0 × 10⁷ 1.35 VEC-8 8 (203.2) 1.1 × 10⁷ 1.34 VEC-9 8(203.2) 2.6 × 10⁸ 0.14  VEC-10 8 (203.2) 1.6 × 10⁷ 1.26

Multi-Layer Constructions Adhesive Skin SKN-1

A one quart (946 mls.) glass jar was charged with 372 grams IOA, 28grams AA and 0.16 grams I-651. The monomer mixture was stirred for 30minutes at 21° C., purged with nitrogen for 5 minutes, and exposed tothe low intensity (0.3 mW/cm²) ultraviolet light until a coatablepre-adhesive polymeric syrup was formed. An additional 0.64 grams I-651and 0.6 grams TMT were subsequently blended into the polymeric syrupusing the high speed mixer. The polymeric syrup was then coated betweensilicone release liners T-10 and T-50 at an approximate thickness of 1to 2 mils (25.4-50.8 μm) and cured by means of UV-A light at 1,500mJ/cm².

Adhesive Skins SKN-2-SKN-4

The procedure generally described in SKN-1 was repeated, according tothe monomer and tackifier compositions listed in Table 7.

TABLE 7 Composition Additives (as pph of Adhesive % Acrylate Acrylate)Skin IOA AA TMT F-85E SKN-1 93.0 7.0 0.15 0 SKN-2 95.0 5.0 0.15 0 SKN-393.0 7.0 0.15 20.0 SKN-4 90.0 10.0 0.10 0

Sample 34

Adhesive skin SKN-1 was laid on a clean 12 by 48 by 0.5-inch (30.5 by121.9 by 1.27 cm) glass plate and the upper silicone release linerremoved. One of the silicone release liners was removed from a sample ofvisco-elastic core VEC-3, and the exposed surface of the core laid overthe exposed adhesive skin of SKN-1. The core and skin were thenlaminated together by manually applying a hand roller over the releaseliner of the visco-elastic core. The release liner covering thevisco-elastic core removed, as was a release liner of another sample ofadhesive skin SKN-1. The skin was then laminated onto the exposed coreby means of the hand roller, resulting in a SKN-1:VEC-3:SKN-1 laminate.The laminate was then allowed to dwell for 24 hours at 50% RH and 70° F.(21.1° C.) before testing.

Samples 35-42

The procedure generally described in Sample 34 was repeated, accordingto the adhesive skin and visco-elastic core constructions listed inTable 8. With respect to Sample 42, the adhesive skin is represented byadhesive transfer tape 467-MP/467-MPF. Physical characteristics of theresultant multi-layer constructions are also presented in Table 8.

Sample 43

A one quart jar glass jar was charged with 405 grams ISA, 45 grams IOAand 0.18 grams I-651, corresponding to the composition “VEC-7” of Table5. The monomer mixture was stirred for 30 minutes at 21° C., purged withnitrogen for 5 minutes, and exposed to the low intensity ultravioletlight until a coatable pre-adhesive polymeric syrup was formed. Anadditional 0.72 grams I-651 and 0.675 grams TMT were subsequentlyblended into the polymeric syrup using the high speed mixer. Thepolymeric syrup was then coated between layers of adhesive transfertapes 467-MP and 467-MPF, at an approximate thickness of 8 mils (203.2μm), and cured by means of UV-A light exposure through the 467-MPF sideat 2,000 mJ/cm².

Samples 44-46

The procedure generally described in Sample 43 was repeated, accordingto the compositions for VEC-8, VEC-9 and VEC-10, respectively, listed inTable 5. Physical characteristics of the visco-elastic cores and of theresultant multi-layer constructions are listed in Table 7 and Table 8,respectively.

TABLE 8 Adhesion To Adhesion To Polyurethane Aluminum Visco- AdhesionAdhesion Adhesive Elastic Peel Force Failure Peel Force Failure SampleSkin Core (N/dm) Mode (N/dm) Mode 34 SKN-1 VEC-3 92 A 77 A 35 SKN-2VEC-3 39 A 59 A 36 SKN-1 VEC-2 46 A 59 A 37 SKN-1 VEC-1 44 A 59 A 38SKN-3 VEC-3 55 A 83 A 39 SKN-4 VEC-3 81 A 83 A 40 SKN-4 VEC-4 88 2B  772B  41 SKN-4 VEC-6 68 A 63 A 42 467- VEC-5 70 A 112 A MP/MPF 43 467-VEC-7 45 2B  39 2B  MP/MPF 44 467- VEC-8 37 C 39 C MP/MPF 45 467- VEC-947 A 49 A MP/MPF 46 467-  VEC-10 53 C 51 C MP/MPF

Damping Performance

DLF values were determined for selected adhesive samples according tothe test method described above. Results are listed in Table 9.

TABLE 9 Number of Loss Factor @ −10° C. Loss Factor @ −20° C. SampleLayers 120 Hz 400 Hz 800 Hz 120 Hz 400 Hz 800 Hz 2 1 0.21 0.23 0.21 0.130.16 0.17 15 1 0.18 0.21 0.21 0.12 0.14 0.15 39 3 0.27 ND ND 0.23 0.27ND 40 3 0.27 0.26 ND 0.24 ND ND 41 3 0.23 0.16 0.12 0.30 0.28 ND 42 30.17 0.20 0.21 0.07 0.07 0.08 43 3 0.26 0.20 0.17 0.27 0.16 0.18 ND =Not detectable

Various modifications and alterations of this disclosure will becomeapparent to those skilled in the art without departing from the scopeand principles of this disclosure, and it should be understood that thisdisclosure is not to be unduly limited to the illustrative embodimentsset forth hereinabove.

We claim:
 1. A viscoelastic damping material comprising: a) a copolymerof: i) at least one monomer of formula I:CH₂═CR¹—COOR²  [I] wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branchedalkyl group containing 12 to 32 carbon atoms; ii) at least one secondmonomer selected from the group consisting of acrylic acid, methacrylicacid, ethacrylic acid, acrylic esters, methacrylic esters and ethacrylicesters; and iii) a copolymerizable multifunctional acrylate; and b) atleast one adhesion-enhancing material selected from the group consistingof inorganic nanoparticles, core-shell rubber particles, isostearylacrylate microspheres, polybutene materials, and polyisobutenematerials.
 2. The viscoelastic damping material of claim 1, wherein thecopolymerizable multifunctional acrylate comprises polyethylene glycoldiacrylate.
 3. The viscoelastic damping material of claim 1 wherein theadhesion-enhancing material comprises silica nanoparticles.
 4. Theviscoelastic damping material of claim 1 wherein the adhesion-enhancingmaterial comprises core-shell rubber particles.
 5. The viscoelasticdamping material of claim 1 wherein R² is a branched alkyl groupcontaining 15 to 22 carbon atoms.
 6. The viscoelastic damping materialof claim 1 wherein R¹ is H or CH₃.
 7. The viscoelastic damping materialof claim 1 wherein the at least one monomer of formula I comprisesisostearyl acrylate.
 8. The viscoelastic damping material of claim 1wherein the copolymer is crosslinked.
 9. The viscoelastic dampingmaterial of claim 1 additionally comprising a plasticizer.
 10. Aviscoelastic construction comprising: a viscoelastic layer comprisingthe viscoelastic damping material of claim 1; and at least one pressuresensitive adhesive layer bound to the viscoelastic layer.
 11. Theviscoelastic construction of claim 10, wherein said viscoelastic layeris sandwiched between two layers comprising a pressure sensitiveadhesive.
 12. The viscoelastic construction of claim 10 wherein R² is abranched alkyl group containing 15 to 22 carbon atoms.
 13. Theviscoelastic construction of claim 10 wherein R² is a branched alkylgroup containing 16 to 20 carbon atoms.
 14. The viscoelasticconstruction of claim 10 wherein R¹ is H or CH₃.
 15. The viscoelasticconstruction of claim 10 wherein said pressure sensitive adhesive layercomprises an acrylic pressure sensitive adhesive.
 16. The viscoelasticconstruction of claim 15 wherein said acrylic pressure sensitiveadhesive is a copolymer of acrylic acid.
 17. A viscoelastic constructioncomprising: a) discrete particles of the viscoelastic damping materialof claim 1 dispersed in b) a pressure sensitive adhesive layer.
 18. Aviscoelastic damping material comprising a copolymer of: i) at least onemonomer of formula I:CH₂═CR¹—COOR²  [I] wherein R¹ is H, CH₃ or CH₂CH₃ and R² is a branchedalkyl group containing 12 to 32 carbon atoms, and ii) a monofunctionalsilicone (meth)acrylate oligomer.
 19. The viscoelastic damping materialof claim 18 wherein R² is a branched alkyl group containing 15 to 22carbon atoms.
 20. The viscoelastic damping material of claim 18 whereinR¹ is H or CH₃.